The invention relates to a device for detecting a gaseous medium in air. An air inlet and an air outlet are formed in the side wall of the shell. A cleaning mechanism, a negative pressure collection mechanism and a detection
assembly are sequentially arranged in the shell in the
airflow direction, the input end of the cleaning mechanism communicates with the air inlet, and the output end of the detection
assembly communicates with the air outlet; the negative pressure collecting mechanism can form
airflow flowing to the air outlet. The cleaning mechanism is used for removing
solid impurities in gas flowing through the cleaning mechanism, and when
airflow generated by the negative pressure collecting mechanism flows through the cleaning mechanism, the cleaning mechanism can be driven by the airflow to move for self-cleaning. The detection
assembly is used for detecting flowing gas. According to the device,
solid impurities in air can be removed, so that the negative pressure collecting mechanism and the detection assembly can operate stably, and the
failure rate is reduced; the cleaning mechanism is driven by airflow, driving assemblies such as a motor do not need to be additionally arranged, the size and weight of the device can be effectively reduced, portability is improved, and operation and maintenance are easy.